1. Field of the Present Invention
The present invention relates to a stress-induced promoter derived from rice and a method for using the same.
2. Prior Art
Plants possess tolerance mechanisms to cope with various types of environmental stresses in nature such as dehydration, high temperature, freezing, or salt stress. Recently, as the stress tolerance mechanism is elucidated at a molecular level, stress tolerant plants have been produced using biotechnological techniques. For example, it has been shown that stress proteins such as LEA proteins, water channel proteins, or synthases for compatible solutes are induced in cells when they are exposed to stress, thereby protecting the cells from such stress. Thus, research has been attempted in which genes such as LEA proteins of barley or detoxification enzymes of tobacco, or genes of synthases for osmoregulatory substances (e.g., sugar, proline, or glycinebetaine) are introduced into host plants. Research using genes encoding w-3 fatty acid desaturase of Arabidopsis thaliana, the D9-desaturase of blue-green algae, or the like, which are modification enzymes of the cellular membrane lipid, has also been attempted. In the above researches, a gene was bound to the 35S promoter of the cauliflower mosaic virus and introduced into a plant. The level of stress tolerance of the recombinant plant was, however, unstable, and the expression level of the introduced gene was low. Thus, none of these was put to practical use.
On the other hand, stress tolerance mechanism is found to be intricately associated with several genes (Shinozaki K, Yamaguchi-Shinozaki K. Gene Expression and Signal Transduction in Water-Stress Response. Plant Physiol. 1997 October; 115(2) p327–334). Accordingly, research whereby a gene, which encodes a transcription factor and which also simultaneously activates the expression of the genes, is ligated to a constitutive promoter and introduced into a plant, thereby enhancing the plant's stress tolerance, has been attempted (Liu et al., (1998) The Plant Cell, 10:1391–1406). However, when several genes are simultaneously activated, the energy of the host plant becomes directed towards the synthesis of the gene product or intracellular metabolism resulting from the gene product. Accordingly, the growth of the plant itself becomes retarded or dwarf.